Mattress innersprings, or simply “innersprings”, made of matrices or arrays of a plurality of wire form springs or coils, have long been used as the reflexive core of mattress padding and upholstery is arranged and attached around the innerspring. Innersprings made of formed steel wire are mass produced by machinery which forms the coils from steel wire stock and interconnects or laces the coils together in the matrix array. With such machinery, design attributes of innersprings can be selected and modified, from the gauge of the wire, the coil design or combinations of designs, coil orientation relative to adjacent coils in the matrix array, and the manner of interconnection or lacing of the coils.
Mattresses and other types of cushions have for decades been constructed using conventional innersprings, which, due to their symmetrical construction resulting from the use of generally symmetrical coils as manufactured by coil production, have two sides (as defined by the coil ends) which provided reflective support. The conventional innerspring typically consists of a series of hour-glass shaped-springs that are adjoined by lacing end convolutions together with cross helical wires. An advantage of this arrangement is that it is inexpensive to manufacture. However, this type of innerspring provides a firm and rigid mattress surface.
Another type of coil that has been used in mattress construction is the pocketed coil. A pocketed coil is a spring wrapped in a cloth cover. The springs are arranged in succession and the pockets are sewn together to form a cohesive unit. This type of innerspring provides a more comfortable mattress surface because the springs become relatively individually flexible, so that each spring may flex separately without affecting the neighboring springs. However, this type of innerspring design is more expensive to construct and also more prone to sagging than the conventional hour-glass shaped, non-pocketed innerspring.
Innerspring designs of the prior art attempt overcome the limitations of existing innerspring designs with varying heights, helical turns, and spring rates along with variations on placement and orientation have all been individually introduced in an effort to improve innerspring design or to compliment a particular mattress design. However, these designs and configurations are typically focused on improving one aspect of mattress design, such as comfort, affordability, ease of manufacture, or durability. And the physical properties, i.e. spring characteristics of single wire springs are constrained by the gauge of wire used, the height of the coil, the number and radius of turns or convolutions in a helical spring body, and the end configurations.